1. Field of the Invention
This invention relates to a self-inking stamping device for performing an inking upstroke, comprising a base part, which is provided with a bearing rim for engaging a surface to be marked and accommodates an ink pad, also comprising a stamping insert, which is accommodated in the base part and reciprocable between the ink pad and the bearing rim and arranged to be inverted during its reciprocation, and an actuating member, which has two end legs in sliding contact with opposite end faces of the base part and displaceable toward the bearing rim against spring force, which actuating member is formed with slots, which extend transversely to the direction in which the actuating member is displaceable and receive a pivot for the stamping insert, which pivot extends through cam slots formed in the end walls of the base part, wherein said stamping insert comprises a frame, which is provided with a printing plate and which is provided at opposite ends with two vertical tracks, each of which receives a pin provided on the adjacent end wall of the base part, and a stamping unit is movably mounted in the frame of the stamping insert and adjustable by screw means in a direction which is normal to the plane of the printing plate and adapted to protrude through an aperture formed in the printing plate.
2. Description of the Prior Art
Self-inking stamping devices of that type are known, e.g., from Austrian Patent Specification Nos. 286,325 and 375,584, which describe such devices in which the stamping insert consists only of a stamping belt unit. In other known self-inking stamping devices the stamping insert consists only of a carrier for the printing plate, which is provided with an invariable script or character image. Other self-inking stamping devices known in practice comprise a stamping insert which includes a stamping belt unit and a printing plate. In said devices, the belts of the stamping belt unit carry the numeral and letter type which is required for a date mark and the printing plate is provided, e.g., the name of a business enterprise and the word "Received on" and/or "Time limit on". Because the stamping belt unit protrudes through the printing plate, the permanent inscription provided by the type on the printing plate can be combined with the changing date mark provided by the stamping belts. But the plates are mostly made of rubber and often vary in thickness. If the stamping device is to produce a uniform imprint, the type on the stamping belts must be arranged in the same plane as the surface of the type on the printing plate. For this purpose the stamping belt unit is mounted in the frame of the stamping insert so as to be adjustable by screw means in a direction which is normal to the plane of the printing plate. The printing plate is adhesively joined to the associated backing plate of the frame and the stamping belt unit is then adjusted to a position in which the surfaces of the type on the stamping belts and the type on the printing plate lie in one plane.
In the prior art, the pivot of the entire stamping insert is held without backlash in the frame of that insert. For this reason an application of printing plates differing in thickness and the corresponding re-adjustment of the stamping belt unit in the frame will necessarily change the distance from the pivotal axis of the stamping insert to the plane that is defined by the surface of the type on the stamping belts and the printing plate. But the pivot of the stamping insert is guided and/or movably mounted in the cam slots formed in the end walls of the base part and particularly in the slots formed in the legs of the actuating member and extending transversely to the direction in which the actuating member is displaceable, and the axis of the pivot determines the position of the entire stamping insert so that a change of the distance from the surface of the type to that pivotal axis will result in irregularities and inequalities regarding the pressure under which the type is applied to the ink pad and/or the surface to be marked.